This invention relates to a method for sterilizing a medical unit comprising at least two connections for a fluid flow pathway where a sterilizing medium flows through the assembly.
The present invention also relates to an apparatus for carrying out this method with a means used for producing and/or providing the sterilizing medium in the system.
Medical units of this type, such as medical filters, in particular blood treating filters which are inserted into the extracorporeal circuit (e.g. dialyzers) must always be as sterile as possible. The same applies to units which are used for applying sterile medicaments.
It is known in practice that medical units of this type are sterilized in sequential steps to make them ready for delivery. The individual steps are carried out separately in different rooms or systems, so that there are unsterile intermediate steps between the individual steps, resulting in a possible loss of sterility.
In the method known from U.S. Pat. No. 4,411,866 (corresponding to German DE 30 12 110 Al), the disclosure of which is hereby incorporated by reference, an artificial kidney is first filled up with a fluid which is not harmful to the human body. The connections of the kidney are then closed. The artificial kidney which is already accommodated in a packing container is subsequently introduced into an autoclave and sterilized in steam at an elevated temperature and under high pressure.
Considerable typical disadvantages of the known kind of method are:
Expensive, expandable special closures or expansion chambers are necessary for compensating for the increase in volume during sterilization in the autoclave; PA0 the closures may nevertheless tear; PA0 not every type of artificial kidney can be sterilized in accordance with the known method; PA0 since the sterilizing operation is carried out with a "quasi-stagnant liquid" in the artificial kidney, non-sterile pockets may be formed with heat bridges in dead corners. PA0 (a) Inserting the unit into a system under pressure-tight coupling of the two connections to a feed conduit and discharge conduit of the system under atmospheric conditions; PA0 (b) passing the sterilizing medium from the system through the unit for a given period; PA0 (c) germproof closing of the two connections in the coupled state, without the same being opened, after completion of the sterilization operation; and PA0 (d) removing the unit from the system as a sterile unit with closed connections. PA0 at least one fastening means which is subjected to atmospheric pressure and used for the temporary pressure-tight coupling of the unit connections and comprises an inlet and an outlet; PA0 at least one conduit from the sterilizing medium means to the inlet of the fastening means; PA0 at least one conduit which is connected to the outlet of the fastening means; PA0 closing members, in particular shut-off valves, in the conduits; PA0 closing of the connections of the unit in the coupled state.
The method which has become known from U.S. Pat. No. 4,810,469 (European Patent Application EP 0 198 100 Al), herein incorporated by reference, goes one step further. In this method an artificial human organ, such as an artificial kidney, is continuously sterilized in an autoclave, namely from the inside with water heated to a sterile temperature and from the outside with superheated steam. The organ is subsequently cooled by a correspondingly cool sterile water, which inwardly flows through the organ, whereby the sterile condition is maintained.
The present invention starts from this known method in which the sterilization operation is carried out continuously.
A considerable disadvantage of the known method and the associated apparatus is that the sterile state might be abandoned when the artificial organ is removed from the autoclave for closing and packaging the same.